CN218896638U - Integrated optical sensor, imaging system and electronic device - Google Patents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
Abstract
Embodiments of the present disclosure relate to integrated optical sensors, imaging systems, and electronic devices. An integrated optical sensor comprising a pinned photodiode, the integrated optical sensor comprising: a semiconductor substrate, comprising: a first semiconductor region having a first conductivity type; a second semiconductor region having a second conductivity type opposite to the first conductivity type; and a third semiconductor region having a second conductivity type; wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region; wherein the third semiconductor region is thicker, less doped and located deeper in the semiconductor substrate than the second semiconductor region; and wherein the third semiconductor region comprises silicon and germanium, wherein the germanium has a first concentration gradient. With embodiments of the present disclosure, the duration of minority carrier collection is reduced.
Description
Technical Field
Implementations and embodiments relate to integrated optical sensors, and in particular, integrated optical sensors including pinned photodiodes.
Background
In recent years, more and more applications such as face recognition, virtual reality, and active car security require high performance, low-profile, and low-cost imaging systems.
In this regard, imaging systems based on the use of indirect time-of-flight (iToF) measurement techniques and benefiting from highly integrated structures and accurate and fast performance meet these expectations particularly well.
More specifically, with periodically modulated excitation obtained from a laser, the distance separating the object to be measured from the imaging system (referred to as an "iToF" imaging system) can be measured indirectly, for example, via phase shift measurement of a signal that is received after reflection on the object relative to the emitted radiation, and the data collection of the optical signal can be extended over several excitation and emission cycles in order to improve the accuracy of the measurement.
Detectors of this type are particularly suitable for applications using radiation whose wavelength is in the near infrared (e.g., 0.94 microns).
As such, these applications are increasingly being implemented, in particular, not only in time-of-flight sensors but also in CMOS imagers.
Typically, the sensor used is an integrated silicon-based sensor.
However, silicon has low absorption power in the infrared and even in the near infrared (e.g., 0.94 microns). For example, a silicon substrate having a thickness of 1 micron has an absorption of 1.7% at a wavelength of 0.94 microns.
This absorption power increases with greater thickness, for example on the order of 6 microns, which is typical of pinned photodiodes of integrated optical sensors.
But silicon devices have low sensitivity in the near infrared. For example, a silicon substrate having a thickness of 6 microns has a quantum efficiency in the range of 7% to 8% at a wavelength of 0.94 microns.
Furthermore, at this thickness, the collection of minority carriers in the pinned photodiode is very slow, which is detrimental.
Thus, there is a need to improve the performance of optical sensors that implement in particular one or more pinned photodiodes, in particular in terms of absorption and/or sensitivity and/or collection speed of minority carriers, most particularly in the near infrared range.
Disclosure of Invention
It is an object of the present disclosure to provide an integrated optical sensor, imaging system and electronic device to at least partially solve the above-mentioned problems of the prior art.
An aspect of the present disclosure provides an integrated optical sensor including a pinned photodiode, the integrated optical sensor comprising: a semiconductor substrate, comprising: a first semiconductor region having a first conductivity type; a second semiconductor region having a second conductivity type opposite to the first conductivity type; and a third semiconductor region having a second conductivity type; wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region; wherein the third semiconductor region is thicker, less doped and located deeper in the semiconductor substrate than the second semiconductor region; and wherein the third semiconductor region comprises silicon and germanium, wherein the germanium has a first concentration gradient.
In accordance with one or more embodiments, wherein the first concentration gradient is a positive gradient, wherein an atomic percent of germanium in the third semiconductor region increases from a bottom of the third semiconductor region toward the first semiconductor region.
According to one or more embodiments, wherein the atomic percentage of germanium for the first concentration gradient increases from 0% to 6%.
According to one or more embodiments, wherein the atomic percent of germanium for the first concentration gradient increases from 3% to 6%.
In accordance with one or more embodiments, wherein the third semiconductor region includes a depletion region and a non-depletion region, the depletion region is in contact with the first semiconductor region and is located above the non-depletion region, and wherein the first concentration gradient is located in the non-depletion region.
According to one or more embodiments, wherein the first concentration gradient is a positive gradient, wherein an atomic percentage of germanium in the non-depletion region increases from a bottom of the non-depletion region towards the depletion region.
According to one or more embodiments, wherein the atomic percentage of germanium for the first concentration gradient increases from 0% to 6%.
According to one or more embodiments, wherein the atomic percent of germanium for the first concentration gradient increases from 3% to 6%.
According to one or more embodiments, wherein the third semiconductor region further comprises silicon and germanium in the depletion region, wherein the germanium has a second concentration gradient, wherein the second concentration gradient is a negative concentration gradient, wherein an atomic percentage of germanium in the depletion region decreases from the non-depletion region towards the first semiconductor region.
According to one or more embodiments, wherein the atomic percent of germanium is reduced from 6% to 0% in the depletion region.
In accordance with one or more embodiments, the depletion region in the third semiconductor region does not include germanium.
In accordance with one or more embodiments, wherein the third semiconductor region comprises a silicon germanium alloy.
In accordance with one or more embodiments, wherein the third semiconductor region is formed of alternating silicon layers and silicon germanium layers.
In accordance with one or more embodiments, the first conductivity type is N-type and the second conductivity type is P-type.
In accordance with one or more embodiments, wherein the semiconductor substrate is a silicon-on-insulator type substrate comprising a buried insulating layer capped by a semiconductor film, and wherein the pinned photodiode is contained within the semiconductor film.
In accordance with one or more embodiments, a sensor includes at least one detection module including a pinned photodiode.
In accordance with one or more embodiments, the pinned photodiode is a component of an imaging system.
In accordance with one or more embodiments, wherein the imaging system is a time of flight (ToF) system.
In accordance with one or more embodiments, wherein the imaging system is a component of an electronic device.
In accordance with one or more embodiments, wherein the electronic device is selected from the group consisting of: tablet computers and cellular mobile telephones.
Another aspect of the present disclosure provides an integrated optical sensor including a pinned photodiode, the integrated optical sensor comprising: a semiconductor substrate, comprising: a first semiconductor region having a first conductivity type; a second semiconductor region having a second conductivity type opposite to the first conductivity type; and a third semiconductor region having a second conductivity type; wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region; wherein the third semiconductor region is thicker, less doped and located deeper in the semiconductor substrate than the second semiconductor region; and wherein the third semiconductor region comprises silicon and germanium, the germanium having a substantially constant atomic percent of germanium of less than or equal to 6%.
In accordance with one or more embodiments, wherein the third semiconductor region includes a depletion region and a non-depletion region, the depletion region is in contact with the first semiconductor region and is located above the non-depletion region, and the non-depletion region includes germanium having a substantially constant atomic percentage.
In accordance with one or more embodiments, wherein the constant atomic percent of germanium is between 4% and 5% in the non-depleted region.
In accordance with one or more embodiments, the depletion region does not include germanium.
According to one or more embodiments, wherein the constant atomic percent of germanium is between 4% and 5%.
In accordance with one or more embodiments, wherein the third semiconductor region comprises a silicon germanium alloy.
In accordance with one or more embodiments, wherein the third semiconductor region is formed of alternating silicon layers and silicon germanium layers.
In accordance with one or more embodiments, the first conductivity type is N-type and the second conductivity type is P-type.
In accordance with one or more embodiments, wherein the semiconductor substrate is a silicon-on-insulator type substrate comprising a buried insulating layer capped by a semiconductor film, and wherein the pinned photodiode is contained within the semiconductor film.
In accordance with one or more embodiments, a sensor includes at least one detection module including a pinned photodiode.
In accordance with one or more embodiments, the pinned photodiode is a component of an imaging system.
In accordance with one or more embodiments, wherein the imaging system is a time of flight (ToF) system.
In accordance with one or more embodiments, wherein the imaging system is a component of an electronic device.
In accordance with one or more embodiments, wherein the electronic device is selected from the group consisting of: tablet computers and cellular mobile telephones.
Yet another aspect of the present disclosure provides an integrated optical sensor including a pinned photodiode, the integrated optical sensor including: a semiconductor substrate, comprising: a first semiconductor region having a first conductivity type; a second semiconductor region having a second conductivity type opposite to the first conductivity type; and a third semiconductor region having a second conductivity type; wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region; wherein the third semiconductor region is thicker, less doped and located deeper in the semiconductor substrate than the second semiconductor region; wherein the third semiconductor region includes a depletion region and a non-depletion region, the depletion region being in contact with the first semiconductor region and being located above the non-depletion region; and wherein the non-depletion region of the third semiconductor region comprises silicon and germanium, wherein the germanium has a positive concentration gradient, wherein the atomic percent of germanium increases from the bottom of the non-depletion region towards the depletion region.
According to one or more embodiments, wherein the atomic percentage of germanium for a positive concentration gradient increases from 0% to 6%.
According to one or more embodiments, wherein the atomic percentage of germanium for a positive concentration gradient increases from 3% to 6%.
In accordance with one or more embodiments, wherein the depletion region comprises silicon and germanium, wherein the germanium has a negative concentration gradient, wherein an atomic percent of germanium in the depletion region decreases from the non-depletion region toward the first semiconductor region.
According to one or more embodiments, wherein the atomic percent of germanium is reduced from 6% to 0% in the depletion region.
In accordance with one or more embodiments, the depletion region in the third semiconductor region does not include germanium.
With embodiments of the present disclosure, the duration of minority carrier collection is reduced.
Drawings
Other advantages and features of the utility model will become apparent from a review of the detailed description of the embodiments and implementations and the accompanying drawings in which:
FIG. 1 illustrates a cross section of a pinned photodiode located within a semiconductor substrate and also illustrates dopant concentration information;
FIG. 2 illustrates a cross-section of a pinned photodiode within a semiconductor substrate and also illustrates the alternation of doped layers;
FIG. 3 schematically illustrates an integrated optical sensor;
FIG. 4 schematically illustrates an imaging system including an integrated optical sensor; and
fig. 5 schematically illustrates an electronic device comprising an integrated optical sensor.
Detailed Description
On the right part of fig. 1, the reference numeral MD generally designates a detection module comprising a pinned photodiode PPD located within a semiconductor substrate, here a silicon-on-insulator (SOI) type substrate.
The module MD is integrated within an integrated circuit IC.
The SOI-type substrate comprises a semiconductor film 1, which semiconductor film 1 is located above a buried insulating layer BX, which in turn is located above a carrier substrate 3.
The thickness Ep of the semiconductor film 1 may be comprised between about 3 and 6 microns, and in this example is of the order of 6 microns.
Photodiode PPD is a buried photodiode formed by a double junction (here, a double p+np junction).
Here, the photodiode PPD is electrically insulated from the remaining portion of the semiconductor film 1 by the deep insulation trench 4.
More specifically, the photodiode PPD includes a first semiconductor region RG1 having N-type conductivity within the semiconductor film 1, the first semiconductor region RG1 being located between a second semiconductor region RG2 (or pinning implant) having P-type conductivity and a third semiconductor region RG3 having P-type conductivity.
The first region RG1 may advantageously be formed in the middle of the module and does not extend to the deep insulation trench 4.
The second region RG2 has a thickness e2 in the order of 0.07 micrometers.
The second region RG2 is at a concentration of about 10 20 atoms/cm 3 P+ doped with a dopant of the group (a).
This pinning injection allows for a greatly reduced dark current of the detection module MD.
The first region RG1 has a thickness e1 on the order of 0.3 micrometers.
The first region RG1 is at a concentration of about 2×10 17 atoms/cm 3 Is N-doped with a dopant of (a).
The third region RG3 has a thickness e3 of the order of 6 micrometers.
The third region RG3 is less doped than the second region RG2 and is located deeper in the substrate.
It is P-doped, wherein the dopant concentration is between 10 14 -10 15 atoms/cm 3 Is in the range of (2).
The third region RG3 may be very lightly doped above 90% of its thickness, but may comprise a more heavily doped P-type P-layer (10 17 To 10 18 atoms/cm 3 ) That is to say here adjacent to or on the buried insulating layer BX.
The third region RG3 includes a depletion region Z30 contacting the first region RG1 and a non-depletion region Z31 below the depletion region Z30.
The depletion region Z30 has a thickness e30 on the order of 2 to 3 microns, the doping of the depletion region Z30 corresponding to the P doping of the non-depletion region Z31 (at 10 14 To 10 15 Atomic/cm 3) with the N-doped "tail" of the second region RG2.
The non-depletion region Z31 has a thickness e31 on the order of 3 to 4 microns and, as indicated above, has a thickness of 10 14 To 10 15 atoms/cm 3 A dopant concentration of the order of magnitude.
Furthermore, the module MD comprises a portion 2 above the upper surface FS Of the semiconductor film 1, which portion 2 comprises (Of conventional construction and known per se) processing circuitry Of the photodiodes, in particular a collection allowing accumulation Of minority carriers in the first region N, and an interconnection region known by the acronym BEOL ("Back End Of Line") to a person skilled in the art.
As illustrated in the left part of fig. 1, the third region RG3 includes silicon and germanium, which may have different concentration profiles.
Thus, according to the first embodiment, preferably in the non-depletion region Z31, the germanium concentration may have a profile PRF corresponding to a substantially constant germanium concentration. In this context, substantially constant means within +/-1 to 3% of the target dopant concentration level throughout the region of interest (i.e., region Z31).
As an example, the atomic percent of germanium is on the order of 4% to 5% throughout the thickness of the non-depletion region Z31, and then suddenly drops to 0 at the depletion region Z30.
The presence of this small amount of germanium (typically having an atomic percentage of germanium of less than 6% in the third region RG 3) allows in particular to improve the absorption coefficient while minimizing the risk of dislocations occurring.
However, the third region RG3 may comprise silicon and germanium, which advantageously have a first concentration gradient GR1 (or GR 10) and a second concentration gradient GR2 (or GR 20).
Gradients GR1, GR2, GR10, and GR20 are examples of possible but non-limiting gradients.
The first concentration gradient GR1 or GR10 is a positive gradient, meaning that the atomic percentage of germanium increases from the buried oxide layer BX toward the first region RG 1.
Regarding gradient GR1, the atomic percentage of germanium increases from 0% to 6% from the bottom of the non-depletion region Z31 to the limit of the depletion region Z30.
Regarding gradient GR10, from the bottom of the non-depletion region Z31 to the limit of the depletion region Z30, the atomic percent of germanium increases from, for example, 3% to 6%.
The second germanium concentration gradient GR2 or GR20 located in the depletion region Z30 is a negative gradient, meaning that the atomic percentage of germanium decreases from the limit of the depletion region Z30 towards the first region RG 1.
More specifically, for each of the second germanium concentration gradients GR2 or GR20, the atomic percentage of germanium is reduced from 6% to 0% in the depletion region Z30.
Alternatively, this second gradient may be "infinite", which corresponds to a sudden transition, here from 6% to 0% (similar to that illustrated with respect to the change in distributed PRF).
In practice, however, the interdiffusion phenomenon of germanium and silicon atoms eases this abrupt transition.
The presence of the concentration gradient GR1 or GR10 allows to reduce the space between the valence and conduction bands of the semiconductor material and to cause a tilt of the conduction band towards the surface of the photodiode, which will cause to obtain an electric field that will accelerate the movement of minority carriers from the third region towards the first region and thus reduce the duration of the collection of minority carriers.
However, the second germanium concentration gradient creates an electric field opposite to the electric field of the first gradient.
By placing this second negative gradient GR2 or GR20 of germanium in the depletion region Z30, it can become negligible compared to the electric field created by the diode itself.
Thus, the duration of the collection of minority carriers will not be negatively affected.
Furthermore, here again, the presence of a small amount of germanium (for example, wherein the average atomic percentage is between 3% and 6%) allows to improve the absorption coefficient while minimizing the risk of dislocation occurrence.
The embodiment of fig. 1, which provides for the presence of a germanium concentration gradient, thus allows for a fast detection modulus with an improved absorption coefficient and reduced dislocation risk.
Although in the embodiment of fig. 1 the third region RG3 is formed of a homogeneous silicon germanium alloy, as illustrated in fig. 2, the third region RG3 may be formed of an alternation of silicon layers 11 and silicon germanium layers 10.
The volume percentage of germanium for each of these layers 11 is chosen such that the final atomic percentage of germanium in the region RG3 follows the considered gradient.
An embodiment of a method for manufacturing the module MD of fig. 1 will now be described.
In the case of an SOI-type substrate, epitaxy is performed above the buried layer BX (and where appropriate the substrate of which the thin layer of silicon is more heavily doped to form a third region RG 3) in order to form the third region RG3, which third region RG3 comprises silicon and germanium.
Silicon germanium epitaxy is a well known step to those skilled in the art.
As an example, siGe epitaxy may be performed by Chemical Vapor Deposition (CVD) using dichlorosilane + germanium + hydrogen chemistry at 900 to 950 ℃ and reduced pressure (10-60 Torr).
Diborane (B) may also be added 2 H 6 ) To obtain a P doping.
To obtain the desired concentration gradient for germanium, the amount of germanium may be adjusted in the epitaxial reactor so that they follow the ramp.
The SiGe epitaxy is then continued by another epitaxy (this time just a conventional and per se known silicon epitaxy) so as to form a first region RG1 after a local ion implantation of the N-type dopant and then a second p+ doped region RG2 after a local implantation of the P-type dopant.
As an example, the conditions of this other epitaxy are substantially the same as those for SiGe epitaxy, optionally with an increase in temperature from 50 ℃ to 100 ℃.
It should be noted that these two epitaxy, which are often performed at the same step, may be performed in the same epitaxy operation and thus may be performed in the same recipe in the same epitaxy reactor and thus often do not require cooling of the wafer between the two types of deposition.
With respect to the production of the third region RG3 as illustrated in fig. 2, in this case a continuous epitaxy of silicon and silicon germanium is performed in order to obtain a stack of layers 11 and 10.
The volume percentage of germanium for each of these epitaxy is selected such that the average final volume percentage of germanium is comprised between 3% and 6% and, where appropriate, follows the concentration gradient under consideration.
Production then continues by conventional formation of deep and shallow trenches and other components of the detection module, regardless of the variant used.
Instead of performing these complete wafer epitaxy, it would also be possible to perform a first complete wafer silicon epitaxy to form the silicon film 1, then to locally etch the semiconductor film (corresponding to the pixels) in the area where the detection module is produced, then to proceed with the SiGe and Si epitaxy mentioned above, then to produce the insulation trenches and the various electronic components of the module MD.
Furthermore, all what has just been described for SOI-type substrates applies to solid (i.e., bulk) substrates.
As illustrated in fig. 3, the integrated optical sensor SNS may comprise several detection modules MD1-MDn arranged, for example, in a row or matrix.
As illustrated in fig. 4, the sensor SNS may be incorporated within an imaging system CM, such as a camera, which in turn may be incorporated within an electronic device APP (fig. 5) of the type, for example, a tablet computer or cellular mobile phone.
The foregoing need is met by replacing silicon with a material having particularly better infrared absorption, while meeting stringent constraints such as, for example, the following: compatibility with microelectronic components located on the front end of the substrate and compatibility with monocrystalline silicon; integratability in the active portion of the semiconductor device (diode and pinned diode); sufficiently small generation of minority carriers; and as low a defect rate as possible.
The material is then advantageously temperature resistant, has good interfacial quality with silicon and with dielectric materials such as silicon dioxide, and generally has good quality (particularly with no or few dislocations, no or few contaminants).
The pinned photodiode includes a first semiconductor region, such as an N-type, sandwiched between two semiconductor regions, such as a P + type surface region and a thicker and deeper P-type region, within a semiconductor substrate.
For example, it is proposed to incorporate a small amount of germanium in the P-type region in order to improve the performance of the optical sensor, in particular in terms of absorption and sensitivity, in particular in the near infrared range, while minimizing the risk of dislocation formation.
It is furthermore proposed to incorporate germanium, for example, in a P-type region having a positive concentration gradient from the bottom of the P-region to the N-region in order to improve the performance of the optical sensor, in particular in terms of the collection speed of minority carriers, in particular in the near infrared range.
In both cases mentioned above (not too large, e.g. a constant amount of germanium and a positive concentration gradient), the germanium concentration profile preferably stops at the beginning of the depletion region of the P-region.
Thus, according to one aspect, an integrated optical sensor is presented comprising at least one detection module comprising a pinned photodiode.
The photodiode includes a first semiconductor region within a semiconductor substrate having a first conductivity type (e.g., N-type conductivity) between a second semiconductor region having a second conductivity type (e.g., P-type conductivity, opposite the first conductivity type) and a third semiconductor region also having the second conductivity type.
The third region is thicker than the second region.
The third region is less doped than the second region. Thus, the third region may be P doped, while the second region may be p+ doped.
In addition, the third region is located deeper in the substrate than the second region.
The third region comprises silicon and germanium, advantageously in small amounts or atomic percentages, for example with an atomic percentage comprised between 3% and 6%, and preferably with at least a first concentration gradient.
The first concentration gradient is advantageously a positive gradient, the atomic percent of germanium increasing towards the first region.
The presence of germanium allows for an improvement in the absorption coefficient of the semiconductor material.
Furthermore, the presence of an advantageously positive concentration gradient allows to reduce the space between the valence and conduction bands of the semiconductor material and to cause a tilting of the conduction band towards the surface of the photodiode, which will cause to obtain an electric field which will accelerate the movement of minority carriers from the third region towards the first region.
Thus, the duration of minority carrier collection is reduced.
The atomic percent of germanium is preferably increased from 0% to 6%.
In addition, limiting the atomic percent of germanium to 6% allows limiting the risk of dislocation occurrence and generally allows the detection module to remain compatible with other steps of manufacturing the optical sensor and other components of the integrated circuit incorporating the optical sensor.
Furthermore, the growth may occur in any possible way, e.g. linearly or in step(s).
The third region typically includes a depletion region and a non-depletion region (referred to as a neutral region), the depletion region being in contact with and above the non-depletion region, and the first concentration gradient preferably being in the non-depletion region.
In addition, it is also preferred that the germanium has a second negative concentration gradient in the depletion region.
This negative gradient of germanium concentration does create an electric field opposite to the electric field caused by conduction band tilt.
By placing a negative germanium gradient in the depletion region, it becomes negligible compared to the electric field created by the diode itself.
For example, the atomic percent of germanium may be reduced from 6% to 0% in the depletion region.
Although relaxed in practice by the interdiffusion phenomenon of germanium and silicon atoms, the decrease in atomic percent of germanium according to the second gradient may be gradual or abrupt (second "infinite" gradient).
According to another aspect, an integrated optical sensor is provided comprising at least one pinned photodiode comprising a first semiconductor region of a first conductivity type within a semiconductor substrate, the first semiconductor region being located between a second semiconductor region of a second conductivity type opposite the first conductivity type and a third semiconductor region of the second conductivity type, the third semiconductor region being thicker, less doped and located deeper in the substrate than the second region, and the third semiconductor region comprising germanium having an atomic percentage of less than or equal to 6% (e.g. comprised between 3% and 6%).
Indeed, as indicated above, the presence of small amounts of germanium, independently of the presence of the germanium concentration gradient, allows to improve the absorption coefficient while minimizing the risk of dislocation occurrence, and generally allows the detection module to remain compatible with other manufacturing steps of the optical sensor and of other components of the integrated circuit incorporating the optical sensor.
According to one embodiment, the non-depletion region comprises germanium having a substantially constant atomic percent.
The constant atomic percentage of germanium is comprised between 4% and 5%, for example.
The third region may comprise a silicon germanium alloy, for example obtained by a ramped gradient in the concentration of dopant (germanium) in the epitaxial reactor, or an alternation of silicon layers and silicon germanium layers.
As described above, the first conductivity type may be N-type and the second conductivity type may be P-type, but it is also possible that the second conductivity type is N-type and the first conductivity type is P-type.
According to one embodiment, the substrate may be a silicon-on-insulator type substrate comprising a Buried insulating layer known by those skilled in the art by the acronym BOX ("Buried Oxide") which is capped by a semiconductor film containing said pinned photodiode.
The sensor may comprise several detection modules, for example arranged in rows or in a matrix.
According to another aspect, an imaging system, such as a camera, is proposed, comprising at least one sensor as defined above.
According to another aspect, an electronic device, for example of the tablet computer or mobile cellular telephone type, is proposed, comprising at least one imaging system as defined above.
According to another aspect, a method for manufacturing an integrated pinned photodiode is provided, for example in the context of manufacturing an integrated optical sensor incorporating the photodiode, the method comprising an embodiment of a first semiconductor region, a second semiconductor region and a third semiconductor region within a semiconductor substrate, the first semiconductor region having a first conductivity type (e.g. N-type conductivity) and being located between the second semiconductor region and the third semiconductor region, the second semiconductor region having a second conductivity type (e.g. P-type conductivity, opposite the first conductivity type), the third semiconductor region also having the second conductivity type, the third semiconductor region being thicker, less doped than the second region and being located deeper in the substrate than the second region.
According to a variant of this aspect, the production of the third region comprises forming a material comprising silicon and germanium, advantageously in small amounts or atomic percentages, for example with an atomic percentage comprised between 3% and 6%, and preferably with at least a first concentration gradient.
According to another variant of this aspect, the production of the third region comprises forming a material comprising silicon and germanium having an atomic percentage less than or equal to 6%, for example comprised between 3% and 6%.
Regardless of the variation, the formation of the material may include silicon germanium epitaxy or continuous epitaxy of silicon and continuous epitaxy of silicon germanium.
Claims (24)
1. An integrated optical sensor comprising a pinned photodiode, the integrated optical sensor comprising:
a semiconductor substrate, comprising:
a first semiconductor region having a first conductivity type;
a second semiconductor region having a second conductivity type opposite to the first conductivity type; and
a third semiconductor region having the second conductivity type;
wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region;
wherein the third semiconductor region is thicker and located deeper in the semiconductor substrate than the second semiconductor region; and
wherein the third semiconductor region comprises silicon and germanium.
2. The integrated optical sensor of claim 1, wherein the third semiconductor region comprises a depletion region and a non-depletion region, the depletion region being in contact with the first semiconductor region and located above the non-depletion region.
3. The integrated optical sensor of claim 2, wherein the third semiconductor region further comprises silicon and germanium in the depletion region.
4. The integrated optical sensor of claim 2, wherein the depletion region in the third semiconductor region does not include germanium.
5. The integrated optical sensor of claim 1, wherein the third semiconductor region comprises a silicon germanium alloy.
6. The integrated optical sensor of claim 1, wherein the third semiconductor region is formed of alternating layers of silicon and silicon germanium.
7. The integrated optical sensor of claim 1, wherein the first conductivity type is N-type and the second conductivity type is P-type.
8. The integrated optical sensor of claim 1, wherein the semiconductor substrate is a silicon-on-insulator type substrate comprising a buried insulating layer capped by a semiconductor film, and wherein the pinned photodiode is contained within the semiconductor film.
9. The integrated optical sensor of claim 1, comprising at least one detection module comprising the pinned photodiode.
10. An imaging system comprising the integrated optical sensor of claim 1.
11. A time-of-flight ToF system comprising the integrated optical sensor according to claim 1.
12. An electronic device comprising an integrated optical sensor according to claim 10.
13. The electronic device of claim 12, wherein the electronic device comprises a tablet computer and/or a cellular mobile phone.
14. An integrated optical sensor comprising a pinned photodiode, the integrated optical sensor comprising:
a semiconductor substrate, comprising:
a first semiconductor region having a first conductivity type;
a second semiconductor region having a second conductivity type opposite to the first conductivity type; and
a third semiconductor region having the second conductivity type;
wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region;
wherein the third semiconductor region is thicker and located deeper in the semiconductor substrate than the second semiconductor region; and
wherein the third semiconductor region comprises silicon and germanium.
15. The integrated optical sensor of claim 14, wherein the third semiconductor region comprises a depletion region and a non-depletion region, the depletion region being in contact with the first semiconductor region and located above the non-depletion region.
16. The integrated optical sensor of claim 15, wherein the depletion region does not include germanium.
17. The integrated optical sensor of claim 14, wherein the third semiconductor region comprises a silicon germanium alloy.
18. The integrated optical sensor of claim 14, wherein the third semiconductor region is formed of alternating layers of silicon and silicon germanium.
19. The integrated optical sensor of claim 14, wherein the first conductivity type is N-type and the second conductivity type is P-type.
20. The integrated optical sensor of claim 14, wherein the semiconductor substrate is a silicon-on-insulator type substrate comprising a buried insulating layer capped by a semiconductor film, and wherein the pinned photodiode is contained within the semiconductor film.
21. The integrated optical sensor of claim 14, comprising at least one detection module comprising the pinned photodiode.
22. An integrated optical sensor comprising a pinned photodiode, the integrated optical sensor comprising:
a semiconductor substrate, comprising:
a first semiconductor region having a first conductivity type;
a second semiconductor region having a second conductivity type opposite to the first conductivity type; and
a third semiconductor region having the second conductivity type;
wherein the first semiconductor region is located between the second semiconductor region and the third semiconductor region;
wherein the third semiconductor region is thicker and located deeper in the semiconductor substrate than the second semiconductor region;
wherein the third semiconductor region includes a depletion region and a non-depletion region, the depletion region being in contact with the first semiconductor region and being located above the non-depletion region; and
wherein the non-depletion region of the third semiconductor region comprises silicon and germanium.
23. The integrated optical sensor of claim 22, wherein the depletion region comprises silicon and germanium.
24. The integrated optical sensor of claim 22, wherein the depletion region in the third semiconductor region does not include germanium.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR2005537A FR3111019B1 (en) | 2020-05-26 | 2020-05-26 | Integrated optical sensor with pinched photodiodes |
| FR2005537 | 2020-05-26 | ||
| US17/324,619 US11757054B2 (en) | 2020-05-26 | 2021-05-19 | Integrated optical sensor with pinned photodiodes |
| US17/324,619 | 2021-05-19 |
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| CN218896638U true CN218896638U (en) | 2023-04-21 |
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| CN202110570140.2A Pending CN113725242A (en) | 2020-05-26 | 2021-05-25 | Integrated optical sensor with pinned photodiode |
| CN202121129725.2U Active CN218896638U (en) | 2020-05-26 | 2021-05-25 | Integrated optical sensor, imaging system and electronic device |
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